Prosthesis



Jan; .10, 1950 T. V. LARS SON ET PROSTHESIS 3 Sheets-Sheet 1 Filed April24, 1946 Jan. 10, 1950 T. v. LARSSON ET AL PROSTHESIS 3 Sheets-Sheet 2Filed April 24, 1946 rlll lll A Jan. 10,1950 T. v. LARSSON-ETAL2,493,884

PROSTHESIS Filed April 24, 1946 3 Sheets-Sheet 5 JMM I n 6 @M 5 PatentedJan. 10, 1950 PROSTHESIS Torsten V. Larsson and Sven H. Dahlback,Skelleftea, Sweden Application April 24, 1946, Serial No. 664,514 InSweden April 26, 1945 9 Claims.

The present invention refers to an arrangement in a prosthesis havingtwo articulated members, such as a leg prosthesis, to render possiblethe locking of the articulation or joint in various angular positionssolely by exerting a pressure in the longitudinal direction of the onemember.

Accordingto the invention, the one member of the prosthesis, forinstance a thigh attachment, is provided with a friction bar or thelike, which. is adapted to cooperate with a locking member swingably ordisplaceably arranged on the other member of the prosthesis, such as alower leg member, said locking member being adapted to be actuated by aforce component acting in the longitudinal direction of the prosthesismember.

The invention is illustrated in the accompanying drawing, wherein Fig; iis an elevation, partly in section, of a leg prosthesis according to theinvention. Fig. 2 is a partially sectioned rear view of the prosthesis.Figs. 3 and 4 are partly sectioned side and rear views, respectively ofa prosthesis articulated in accordance with the present invention.

In the drawing, l designates the thigh attachment of a leg prosthesis,which is provided at the lower end thereof with a transversely extendingsleeve 2 having journals 3 for a lower leg member screwed therein, ontowhich a foot-member is articulated in known manner by means of athreaded bolt 5.

According to the invention, a metal bar I is secured to the transversesleeve 2, said metal bar 7 being shaped on a circular arc and having itscenter coinciding with the axis of the journals 3. Rotatably mounted onthe sleeve 2 is a strap 8 or the like, which is rigidly connected to across stay 9 secured in the upper portion of the lower leg member.Pivotally mounted in the strap 8 by means of journals Ill is a bellcrank lever ll, !2, one lever arm I! of which is provided with a slot l3having the metal bar I thrust therethrough. Bearing on the other leverarm 12, which is actuated by means of a spring [4, is a rod 15, which inthe longitudinal direction is adjustably secured to a threaded sleeve l6 attached by a compression spring l? to the upper end of a rod 18, thelower end of which is branched into four branch members 2t, 2!, 22, 23extending each through bushing type buffers l9 and an aperture 24, 25,26 and 2?, respectively, in the lower portion of the lower leg, that isto say through a front hole 24, a rear hole 25 and a lateral hole 26 and2! respectively on either side, said branch members bearing on the footmember 6 while being guided, if 55 desired, by means of the pins 2.3 inapertures 23 provided in the foot member.

In the embodiment shown in Figs. 3 and 4, there is inserted asubstantially oval piece of rubber 33 between the lower leg member s andthe foot mem ber 6, said rubber piece having a plane upper surface SIand a plane lower surface 32. Molded and vulcanized into the upperportion of the rubber piece 36 is a metal ring 33 having screw bolts 34secured thereto, which extend through the upper surface it! of therubber piece and serve for the attachment of the rubber piece to thelower end 35 of the lower leg member by means of nuts 36. The lowerportion of the rubber piece also has a metal ring 3? molded andvulcanized into the same, said metal ring having screw bolts 38 securedthereto, which project through the lower surface 32 of the rubber pieceand serve for the attachment of the rubber piece to the upper end wall39 of the foot member 6 by means of nuts 49. Through this rubber piece,the foot member 6 will have a certain resilient mobility impartedthereto relatively to the lower leg member. To increase this mobilitywithin certain limits, a circumferentially extending horizontal slot isprovided in the rubber piece, said slot terminating at its extreme innerend by an enlarged portion 42. Preferably, the slot dl is deeper and,perhaps, wider at the front and rear to facilitate greater mobility in aplane in the longitudinal direction of the foot member.

As will appear from the drawing, a resilient articulation of the footmember is rendered possible in all directions, which movement is clampedwhen the opposite faces 43 and M of the slot il abut against each other.Instead of being united with common molded-in rings, the screw bolts 3dand 38 may be provided with individual anchoring piecesfrom sheet metalmolded into the rubber.

The arrangement according to the construction shown in Figs. 1 and 2operates as follows: When the foot member is caused to bear on theground, it will actuate one or more of the branch members zc -2s, sothat the rod it is displaced in its longitudinal direction and the rod 55 is caused to swing the bell crank lever Ii, I2, against the action ofthe spring M, in a manner such that the edges of the slot is get jammedwith the bar 1' so as to lock the lower leg member relatively to thethigh attachment, independently of the angular position of these membersrelatively to each other. When the leg is raised and the pressure of thefoot member on the ground ceases, the lever arm Q? will be de-' pressedby the spring it, the edges of the slot The invention is not restrictedto the leg prosthesis, but may also be applied in arm prostheses or handprostheses.

Having now described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. In a leg prosthesis including articulated thigh, lower leg and footmembers, means for locking the articulation between the thigh and lowerleg members at any arbitrary angular position by an application ofpressure upon the foot 7 member, said locking means comprising, astationary arcuate locking bar secured to the thigh member in the planeof articulation, a bellcrank locking lever pivotally securedintermediate its 7 ends to the lower leg member, one arm of said leverbeing provided with a sharply edged slot receiving said locking bar, andan actuator member within and displaceable in the longitudinal directionof the lower leg member for engagement with the other arm of said lever,said t actuator member being displaced upwardly in response to pressureapplied thereto from the foot member to thereby rock said lever andcause the sharp edges of said slot to jam and lock against the upper andlower faces of said locking bar.

2. A leg prosthesis as defined in claim 1 wherein the articulationbetween the lower leg and foot members is constituted solely by asubstantially oval resilient body secured at its upper and lowersurfaces to the leg and foot members, respectively, said resilient bodybeing provided with a circumferentially extending horizontal slot, theopposite faces of which abut one another upon articulation of the footmember to thereby exert a' damping action on the foot member.

3. A leg prosthesis as defined in claim 1 wherein the lower end of saidactuator member terminates in a plurality of spaced branches each ofwhich abuts against the foot member.

4. A leg prosthesis as defined in claim 1 wherein the lower end of saidactuator member terminates in two pairs of branches at right angles toeach other each of said branches abutting against the foot member.

'5. A leg prosthesis as defined in claim 1 wherein said actuator memberis constituted by a rod provided with a resiliently compressible member.

6. A prosthesis having a foot member articusilient body secured at itsupper and lower surfaces to said leg and foot members, respectively,said resilient body being provided with a circumferentially extendinghorizontal slot, the opposite faces of which abut one another uponarticulation of the foot member to thereby exert a damping action on thefoot member.

. 7. A prosthesis having a foot member articulated to a lower legmember, the articulation bein constituted solely by a substantially ovalresilient body secured at its upper and lower surfaces to said leg andfoot members, respectively, said resilient body being provided with acircumferentially extending horizontal slot which is deeper at the frontand rear portions of the prosthesis than at the sides thereof, theopposite faces of said slot abutting one another upon articulation ofsaid front member to thereby exert a damping action on the foot member.

8. A prosthesis having a foot member articulated to a lower leg member,the articulation being constituted solely by a substantially ovalresilient body secured at its upper and lower surfaces to said leg andfoot members, respectively, said resilient body being provided with acircumferentially extending horizontal slot which is wider at the frontand rear portions of said prosthesis than at the sides thereof,theopposite faces of said slot abutting one another upon articulation ofsaid foot member to thereby exert a damping action on the foot member.

9. In a limb prosthesis including articulated upper and lower limbs,means for locking the articulation between said limbs at any arbitraryangular position, said locking means comprising, a stationary arcuatelocking bar secured to one of said limbs in the plane of articulation, abellcrank locking lever pivotally secured intermediate its ends to theother limb, one arm of said lever being provided with a sharply edgedslot receiving said locking bar, and an actuator member within anddisplaceable in the longitudinal direction of said other limb to engagethe other arm of said lever and rock the latter thereby causing theedges of said slot to jam and lock against the opposite faces of saidlocking bar.

'1. V. LARSSON. smN H. DAI-ILBACK.

REFERENCES CITED The following references are of record in the V file ofthis patent? lated to a lower leg member, the articulation be- UNITEDSTATES PATENT S Number Name Date 2,315,795 Johnson et al. Apr. 6, 1943FOREIGN PATENTS Number Country Date 314,830 Ger-many -l Oct. 15, 1919

